QuickBooks Online sync error: Missing required data for: quantity.

Why the sync error occurs

This error occurs when receivables invoices with item quantities in Cashflow360℠ try to sync to QuickBooks Online, but inventory tracking isn't enabled in QuickBooks Online. Inventory tracking is required to record quantities on invoices in QuickBooks Online.

How to fix the sync error

Enable inventory tracking in QuickBooks Online, and sync again.